Solar-wind flow past the planets Earth, Mars, and Venus
Numerical analysis of solar wind interactions with nonmagnetic planets based on equations of magnetohydrodynamics for perfect gas
Rizzi, A. W.↗
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Horizontal plasma flow velocities in the ionosphere of Mars - A test case for the solar wind interaction
On the apparently nonmagnetic planets Mars and Venus, ionospheric plasma can be driven from the day to the nightside by two different mechanisms: (1) the pressure gradient force across the terminator, and (2) a solar wind-induced force via a viscous boundary layer interaction. Calculations of the horizontal flow velocities in the ionosphere of Mars using the two mechanisms produce results differing by an order of magnitude. It is pointed out that the detailed observations of the horizontal flow velocity in the ionosphere of Mars may provide a test case for the resolution of some problems relating to the interaction of the solar wind with the planets Mars and Venus.
Singhal, R. P.↗
The Search for Life on Mars
For centuries, the planet Mars has been regarded as a possible abode for life. Serious searches for the signatures of life began in the 19th century, and continue via telescopic investigations and landed missions. While early work focused on phenomenology and bordered on fantasy, modern scientific inquiry has emphasized the search for chemical signatures of life in the soil and rocks at the planet's surface, and the search for biomarker gases in the atmosphere. Living systems produce more than 90% of Earth's atmospheric methane; the balance is of geochemical origin. The discovery of methane on Mars will be described, along with the ongoing extended search for clues to its origins. The possible origins of Mars methane will be discussed in the context of terrestrial analogue sites where geologic and biologic methane production now occurs - ranging from sub-permafrost zones in the arctic to hydrothermal vents in the deep ocean. Terrestrial organisms that could prosper on Mars today will be mentioned. I will briefly touch upon experiments conducted by landed spacecraft, ranging from the Viking Life Science Experiments in 1976 to the impending Mars Science laboratory, and the Trace Gas Orbiter and ExoMars missions now being developed for flight in the coming decade.
Mumma, Michael J.↗
Viking: The exploration of Mars
Photographs of the planet Mars generated by the Viking Mars program are presented and discussed. The Martian surface and its volcanoes receive particular attention. In addition, the atmosphere, temperature, surface craters, polar regions, and composition of Mars are briefly reviewed. Planetary evolution is considered. The highlights of the Mariner program for Mars are given.
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Carbonate Mineral Formation on Mars: Clues from Stable Isotope Variation Seen in Cryogenic Laboratory Studies of Carbonate Salts
The geologic history of water on the planet Mars is intimately connected to the formation of carbonate minerals through atmospheric CO2 and its control of the climate history of Mars. Carbonate mineral formation under modern martian atmospheric conditions could be a critical factor in controlling the martian climate in a means similar to the rock weathering cycle on Earth. The combination of evidence for liquid water on the martian surface and cold surface conditions suggest fluid freezing could be very common on the surface of Mars. Cryogenic calcite forms readily when a rise in pH occurs as a result of carbon dioxide degassing quickly from freezing Ca-bicarbonate-rich water solutions. This is a process that has been observed in some terrestrial settings such as arctic permafrost cave deposits, lakebeds of the Dry Valleys of Antarctica, and in aufeis (river icings) from rivers of N.E. Alaska. We report here the results of a series of laboratory experiments that were conducted to simulate potential cryogenic carbonate formation on the planet Mars. These results indicate that carbonates grown under martian conditions (controlled atmospheric pressure and temperature) show enrichments from starting bicarbonate fluids in both carbon and oxygen isotopes beyond equilibrium values with average delta13C(DIC-CARB) values of ~20.5%0 which exceed the expected equilibrium fractionation factor of [10(sup 3) ln alpha = ~13%0] at 0 degC. Oxygen isotopes showed a smaller enrichment with delta18O(H2O-CARB) values of ~35.5%0, slightly exceeding the equilibrium fractionation factor of [10(sup 3) ln alpha = ~34%0 ] at 0degC. Large kinetic carbon isotope effects during carbonate precipitation could substantially affect the carbon isotope evolution of CO2 on Mars allowing for more efficient removal of 13C from the Noachian atmosphere enriched by atmospheric loss. This mechanism would be consistent with the observations of large carbon isotope variations in martian materials despite the relative paucity of carbonate minerals in the martian crust.
Socki, Richard↗
Aerospace vehicle design, spacecraft section. Volume 2
The next major step in the evolution of the space program is the exploration of the planet Mars. In preparation for this, much research is needed on the problem of surveying the planet surface. An aircraft appears to be a viable solution because it can carry men and equipment large distances in a short period of time as compared with ground transportation. The problems and design of an aircraft which would be able to survey the planet Mars are examined.
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Petrogenesis of the SNC (shergottites, nakhlites, chassignites) meteorites - Implications for their origin from a large dynamic planet, possibly Mars
Comprehensive chemical data are presented on the shergottites Shergotty, Zagami, Allan Hills (ALHA) 77005, and the new member Elephant Moraine (EETA) 79001 using results of sequential instrumental and radiochemical neutron activation analysis. The close relationship of the Antarctic shergotites indicates that ALHA 77005 is a residual source produced by incongruent melting of a source similar in bulk composition to EETA 79001A and that EETA 79001B and the interstitial phases in EETA 79001A are the melts produced by such melting episodes. The large ion lithophile LIL) trace element abundanced of the shergottites require variable but extensive degrees of nomodal melting of isotopically constrained parent sources. The SNG sources are consistent with their derivation by extensive fractionation of a primitive magma initially produced from a source having chondritic refractory LIL trace element abundances. Petrogenetic and age relationships among SNC meteorites suggest a single complex-provenance on a dynamic planet not unlike earth, probably Mars.
Smith, M. R.↗
Planetary surface structure and evolution of Mars
The surface of the planet Mars is characterized by two different hemispheres: old densely cratered structures in the Southern Uplands, and sparsely cratered younger topographically lower regions covering approximately the northern third of the planet's surface. The model for explaining these global surface structures is characterized by the following features: (1) homogeneous accretion of Mars; (2) formation of a metal melt layer; (3) northward translation of the undifferentiated core due to a Rayleigh-Taylor instability; (4) vigorous convection in the southern parts and formation of the Southern Uplands' crust; (5) fragmentation of the primordial core, slowly dissolving rockbergs, beginning of Tharsis uplift and volcanism; (6) formation of the Northern Lowlands' crust from only weakly differentiated silicatic material; and (7) reaching of the present state with symmetrically placed core and further thermal evolution.
Franck, Siegfried↗
Extraterrestrial water of possible Martian origin in SNC meteorites: Constraints from oxygen isotopes
Many lines of evidence suggest that the SNC group of meteorites (Shergotty-Nakhla-Chassigny) are derived from the planet Mars. Because SNC meteorites have water, they may contain information on the origin and fate of water on the planet Mars. The first measurements are presented of delta O-18 and delta O-17 of water extracted from SNC's. The water analyses are displayed with each meteorite designated. The isotopic composition is shown of the SNC waters relative to the SNC whole rocks and the terrestrial line. The O-17 excess is shown of the SNC water as a function of pyrolysis temperature. And delta O-18 values are displayed of the water as a function of pyrolysis temperature for the four SNC meteorites. The analyses are briefly examined.
Karlsson, H. R.↗
Theoretical estimates of the average surface and atmospheric temperatures on mars
Average surface temperature of planet mars computed from radiation equilibrium
SURFACE TEMPERATURE↗
Performance Testing of Yardney Li-Ion Cells and Batteries in Support of Future NASA Missions
NASA requires lightweight rechargeable batteries for future missions to Mars and the outer planets that are capable of operating over a wide range of temperatures, with high specific energy and energy densities. Due to the attractive performance characteristics, Li-ion batteries have been identified as the battery chemistry of choice for a number of future applications. For example, JPL is planning to launch another unmanned rover mission to the planet Mars. This mission, referred to as the Mars Science Laboratory (MSL), will involve the use of a rover that is much larger than the previously developed Spirit and Opportunity Rovers for the 2003 Mars Exploration Rover (MER) mission, that are currently still in operation on the surface of the planet after more than five years. Part of the reason that the MER rovers have operated so successfully, far exceeding the required mission duration of 90 sols, is that they possess robust Li-ion batteries, manufactured by Yardney Technical Products, which have demonstrated excellent life characteristics. Given the excellent performance characteristics displayed, similar Li-ion batteries have been projected to successfully meet the mission requirements of the up-coming MSL mission. In addition to future missions to Mars, Li-ion technology is attractive for a number of other future NASA applications which require high specific energy, rechargeable batteries. To ascertain the viability of using Li-ion batteries for these applications, a number of performance validation tests have been performed on both Yardney cells and batteries of various sizes. These tests include mission simulation tests, charge and discharge rate characterization testing, cycle life testing under various conditions, and storage testing.
Smart, M. C.↗
AGE (Argon Geochronology Experiment): An Instrument for Geochronology on the Surface of Mars
As our knowledge of the planet Mars continues to grow, one parameter that remains elusive is the absolute chronology of the planet s geological history. Although crater counts have provided a robust relative chronology, impactor fluxes are poorly enough known that there are places on Mars where the absolute age is uncertain by a factor of two or more. To resolve these uncertainties, it will be necessary to either analyze well-documented samples returned to the Earth from the Martian surface or to perform in situ measurements with sufficient precision. Sample return is still at least a decade away, and even then it might be from a biologically interesting area that might be geologically complex. Hence an in situ measurement, within an uncertainty of 20% or better, could greatly improve our knowledge of the history of Mars. With funding from the Planetary Instrument Definition and Development Program (PIDDP), we have been working on an instrument to perform potassium-argon (K-Ar) and cosmic-ray exposure (CRE) dating in situ on the surface of Mars. For either of these techniques, it is necessary to measure the abundance of one or more major or minor elements (K in the case of KAr; all majors and minors in the case of CRE) and the abundance and isotopes composition of a noble gas (Ar in the case of K-Ar; He, Ne and Ar for CRE dating). The technology for either of these types of measurements exists, but has never before been integrated for a spacecraft. We refer to the instrument as AGE, the Argon Geochronology Experiment (although we will measure the noble gases He and Ne as well for CRE ages). We report here on the basic components that go into such an instrument, both those that use existing technology and those that had to be developed to create the integrated package.
Swindle, T. D.↗
The use of activity-based cost estimation as a management tool for cultural change
It will be shown that the greatest barrier to American exploration of the planet Mars is not the development of the technology needed to deliver humans and return them safely to earth. Neither is it the cost of such an undertaking, as has been previously suggested, although certainly, such a venture may not be inexpensive by some measures. The predicted costs of exploration have discouraged serious political dialog on the subject. And, in fact, even optimistic projections of the NASA budget do not contain the resources required, under the existing development and management paradigm, for human space exploration programs. It will be demonstrated that the perception of the costs of such a venture, and the cultural responses to the perceptions are factors inhibiting American exploration of the moon and the planet Mars. Cost models employed in the aerospace industry today correctly mirror the history of past space programs, and as such, are representative of the existing management and development paradigms. However, if, under this current paradigm no major exploration programs are feasible, then cost analysis methods based in the past may not have great utility in exploring the needed cultural changes. This paper explores the use of a new type of model, the activity based cost model, which will treat management style as an input variable, in a sense providing a tool whereby a complete, affordable program might be designed, including both the technological and management aspects.
Mandell, Humboldt↗
More about the moment of inertia of Mars
Differences between Mars and other terrestrial planets are discussed. Unlike other terrestrial planets, Mars has two nonhydrostatic components of moments of inertia that are nearly equal. The most probable value of I/MR-squared is slightly less than 0.3650.
Kaula, William M.↗
On Mars
The following aspects of the planet Mars were assessed directly and indirectly by the Viking lander and Viking orbiter spacecraft: the atmosphere, craters, volcanoes, terrain, geology, and evolution. Descriptions of these aspects are included herein. It is concluded that though life is certainly not abundant on Mars, the possibility still exists that some form of life is extant there.
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A consensus approach to planetary protection requirements: recommendations for Mars lander missions
Over the last several years, the nature of the surface conditions on the planet Mars, our knowledge of the growth capabilities of Earth organisms under extreme conditions, and future opportunities for Mars exploration have been under extensive review in the United States and elsewhere. As part of these examinations, in 1992 the US Space Studies Board made a series of recommendations to NASA on the requirements that should be implemented on future missions that will explore Mars. In particular, significant changes were recommended in the requirements for Mars landers, changes that significantly alleviated the burden of planetary protection implementation for these missions. In this paper we propose a resolution implementing this new set of recommendations, for adoption by COSPAR at its 30th meeting in Hamburg. We also discuss future directions and study areas for planetary protection, in light of changing plans for Mars exploration.
NASA Discipline Number 99-99↗
Ridge systems of Mars
Mare-type ridges on the Planet Mars were mapped and described based on Viking images. The ridges mapped range from 5 to 400 km long and 1 to 8 km wide. Most ridges on Mars are on plains and plateau units; 4,321 ridges with a total length of 153,835 km were mapped on these unit types. Ridges which resemble lunar mare ridges were also mapped in craters, basins, and several volcanic calderas on Mars. Mapping of ridges on a global scale reveals that they are preferentially developed in older, thinner plains units probably of flood basalt origin. Measuring the trends of ridges in plains units on Mars shows that there is a planetwide predominance of north, northwest and northeast trends. It is proposed that ridges are compressional tectonic features which have formed in response to changes in the planet's rotational equilibrium figure early in its history. In addition, the Tharsis uplift has created a regional stress system which accounts for the trends of ridges in areas near by. Ridges in craters and basins are similarly caused by shortening across the basin in response to regional stresses.
Gifford, A. W.↗